The ways in which spouses support each other can actually have significant bearing on their overall cardiovascular health, a new study has found.

The findings reveal that when both partners perceive the support they get from each other as ambivalent - that is, sometimes helpful and sometimes upsetting - each partner's levels of coronary artery calcification (CAC) tend to be particularly high.

"Most prior work has ignored the fact that many relationships are characterised by both positive and negative aspects - in other words, ambivalence," said Bert Uchino, psychological scientist of the University of Utah.

The researchers instructed 136 older couples (63 years old, on average) to fill out questionnaires measuring their overall marriage quality, as well as their perceived support from their spouse.

Specifically, they indicated how helpful or how upsetting their spouse was during times when they needed support, advice, or a favour.

Researchers found that about 30 per cent of individuals viewed their partner as delivering positive support, whereas 70 per cent viewed their partner as ambivalent - sometimes helpful and sometimes upsetting.

Using a CT scanner to check for overall calcification in the participants' coronary arteries, researchers found that CAC levels were highest when both partners in the relationship viewed each other as ambivalent.

When only one partner felt this way, the risk was significantly less. The effect was independent of gender, meaning that these associations were comparable for husbands and wives.

Given that the participants were married for an average of 36 years, one might predict that overall marital satisfaction would have a significant impact on this cardiovascular risk factor - but the researchers didn't find that to be the case.

It was the positive and negative aspects of lending support that were most significant in predicting cardiovascular health, suggesting that these factors exert their effects independently of overall marital quality.

It's not exactly clear why this is the case, but the researchers hypothesise that when both partners perceive each other as a source of ambivalence, it changes their behaviour toward one another.

"The findings suggest that couples who have more ambivalent views of each other actively interact or process relationship information in ways that increase their stress or undermine the supportive potential in the relationship," said Uchino.

"This, in turn, may influence their cardiovascular disease risk," said Uchino.